Nine HMO members of the HMO Research Network will form a Center for Education and Research in Therapeutics (CERT). These HMOs, with a total population of 7.1 million, will develop and use infrastructure to support a wide range of collaborative population based investigations and activities relevant to therapeutics. All of these HMO's have research experience using their demographic data, automated medical record linkage systems, information about the organization and delivery of medical care, and the ability to intervene at an organizational level to modify care. They have collaborated in joint pharmacoepidemiology research, and they also participate in an NIH funded Cancer Research Network. The CERT will engage in three types of activities: l) Create and maintain infrastructure to support research on, and improved use of, therapeutics. 2) Perform core studies in all HMOs of prescribing patterns, the impact of drug dosing on health outcomes, and the impact of health policy decisions on drug adherence. 3)Strengthen research and education collaborations among CERT centers. Infrastructure development will include a) specification of each HMO's pharmacy dispensing data, data dictionaries, data transfer specifications and creation of internet based websites to support individual studies, b) characterization of pharmacy benefits for HMOs' members, and c) assessment of the completeness of pharmacy data for important subsets of HMOs' members. The CERT infrastructure will complement the Cancer Research Network's, thereby avoiding duplication. However, the CERT will pursue a wide range of topics not restricted to those related to cancer. The core studies will be: a) (prescribing patterns) analysis of the frequency and reasons for antibiotic use in pediatrics, b) (impact of dosing on outcomes) assessment of the relationship between ACE inhibitor dosing in congestive heart failure and hospitalization, and c) (impact of policy on adherence) evaluation of the effect of changing drug co-payment requirements on diabetic patients' use of hypoglycemic agents. Each study represents a class of studies we anticipate the CERT will undertake, builds on experience the participating HMOs, will provide information that can have direct utility for the HMOs' delivery systems, and will serve as the basis for additional investigation using other funding sources.